Air conditiioning device having at least one heat pipe, in particular thermosiphon

ABSTRACT

The invention relates to an air conditioning device having at least one heat pipe ( 100 ), in particular a thermosiphon, having at least one electro- or magnetocaloric material ( 4 ) under at least temporary influence of an electrical and/or magnet field, and having a heat transfer oriented from one first end to another second end of the heat pipe. A plurality of these heat pipes, having electro- or magnetocaloric materials integrated or arranged therein, are preferably contained, connected in series in a cascade-like manner and optionally connected to one another via heat exchangers or switchable heat flow regulators.

BACKGROUND

The invention concerns an air conditioning device with at least one heat pipe, in particular a thermosiphon.

Heat pipes are distinguished by a high heat flow density and excellent heat transfer properties, so that at a first thermal contact end (also called the evaporator), a liquid working medium is evaporated and at the other thermal contact end (also called the condenser) of the heat pipe—which is initially colder there—the working medium vapor is condensed and thus releases its latent evaporation heat again as condensation heat, wherein a heat transfer by phase change of the working medium with release of latent evaporation or condensation heat implies a particularly favorable and advantageous efficiency of the heat transfer.

Heat pipes are therefore used as highly efficient heat transmitters, e.g. for chip cooling in computers or for heat dissipation from oil pipelines in permafrost ground. The heat pipe is an encapsulated volume filled with a working medium (e.g. water or ammonia). The pressure in the heat pipe is set such that at the desired working temperature, the working medium is present in both liquid and in gaseous form. By heating one side of the heat pipe, the working medium evaporates, and the working medium condenses on the cold side. The liquid working medium may be transported back either under capillary forces (heat pipe) or under gravity ((dual-phase) thermosiphon).

Secondly, today cooling and air conditioning systems are usually compressor-based and therefore require a refrigerant, wherein however usually the latter are not environmentally friendly or easy to handle, in some cases being highly flammable.

It is also known that cooling devices can be produced using thermoelectric generators or Peltier elements as an alternative to such compressor-based systems. These effects however have only a relatively low temperature differential or low efficiency, so that cooling elements have also been developed using the electro- or magnetocaloric effect of corresponding electro- or magnetocaloric materials.

By application of an electrical and/or magnetic field to an electrocaloric or magnetocaloric material, this changes temperature and is usually heated because of the orientation of the electrical or magnetic moments and the associated reduction in entropy. If a heat exchanger is coupled to such materials present in an electrical and/or magnetic field, this heat can be extracted and the material cooled back to ambient temperature. If now the electrical and/or magnetic field is switched off, the material cools because of the resulting disorder of the electrical or magnetic moments, so that by coupling the material to a reservoir, it can be cooled to temperatures below ambient temperature. This is known as the electrocaloric or magnetocaloric effect. If the temperature change on application of a field is positive (e.g. in ferro- and paramagnetic substances), we refer to a conventional (positive) effect, whereas for a negative temperature change on application of the field, we refer to a negative effect (e.g. for systems coupled anti-ferromagnetically).

The applied electrical and/or magnetic field may also cause a change in the crystal structure, wherein the structural change in entropy also leads to a cooling or heating effect. This is designated the inverse caloric effect. This effect may support the above-mentioned electro- or magnetocaloric effect, wherein the two effects are added, or counter this, wherein then the effects are subtracted.

These effects or processes may be used for air conditioning or refrigeration.

A refrigeration system coupling a plurality of heat pipes with a magnetocaloric material block in the influence of a magnetic field is known from US 2004/0182086 A1. A further improvement in the heat transfer characteristic between the magnetocaloric material and the working medium of the heat pipes is however required to achieve higher cooling performance, since the magnetocaloric material remains in contact with the outer periphery of the heat pipes, wherein the contact is equivalent to a thermal resistance. A coupling of unidirectional heat pipes with electrocaloric elements is also shown in U.S. Pat. No. 4,757,688 A1.

SUMMARY

The invention is based on the object of providing an air conditioning device, in particular a heat pump, which contributes to both heating and cooling of an environment of the air conditioning device with improved efficiency. In particular, this takes place utilizing the latent heat of a working medium.

This object is achieved with an air conditioning device having one or more features of the invention.

The invention is distinguished in that the thermally active electrocaloric or magnetocaloric material is integrated in a heat pipe, in particular a thermosiphon, wherein it is ensured in particular that the heat pipe has good thermal conductivity for heat in one direction but allows practically no perceptible heat transport in the other, opposing direction (thermal diode), and here utilizes the latent heat of the working medium, whereby a high cooling power can be achieved.

Between the electro- or magnetocaloric material in the heat pipe and the (at least one) working medium therein, a first heat transfer region is formed in which the electro- or magnetocaloric material is placed under the field influence of an electrical and/or magnetic field, such that it transfers its heat arising from the entropy change to the working medium, wherein to increase the efficiency, preferably its Curie temperature is close to the working temperature. In this way, the working medium transferred into its gaseous or vapor phase by the heat application has a higher energy content, and the received heat is transported to a second, generally upper heat transfer region of the working medium, where this meets at least one heat exchanger or condenser structure on which the working medium condenses in order to transfer its latent heat, whereupon it returns to the first heat transfer region. Preferably, this takes place as a thermosiphon under the influence of gravity.

Preferably, however, the condensation region or condenser of the heat pipe is configured firstly as an electro- or magnetocaloric element which, under the influence of an electrical and/or magnetic field, itself forms an electro- or magnetocaloric heat transfer structure and in this way achieves a potentiation of the heating effect—or the cooling effect at the opposite end—in the sense of a heat pump.

In this way, it is possible to connect several heat pipes together in a cascade arrangement.

In another preferred embodiment, in particular also a plurality of such heat transfer regions with electro- or magnetocaloric material may be arranged in portions inside a single heat pipe, wherein these simultaneously seal the heat pipe pressure-tightly, so that a plurality of working chambers are created inside a heat pipe which are preferably each delimited by an electro- or magnetocaloric material element (also however, in a thermosiphon which works with gravity as a return force for the working medium, an upper end of the respective working region may be formed by a condenser arrangement).

Inside such a segmented heat pipe, different working temperatures, working media and magnetocaloric materials with different Curie temperatures may be used.

By the preferred arrangement of the electro- or magnetocaloric material inside the heat pipe between a first heat transfer region, e.g. in a first lower region thereof, and preferably a second e.g. upper heat transfer region thereof in direct wetting contact with the working medium of the heat pipe (e.g. water), an internal thermal contact occurs between the electro- or magnetocaloric material and the liquid or gaseous or vaporous working medium inside the heat pipe; hence there is a particularly high efficiency of the electro- or magnetocaloric effect for heat output from the heat pipe in the region of its in particular upper end in which the evaporated working medium condenses, and for cooling (heat extraction) from the heat pipe in the region of its in particular lower end in which the electro- or magnetocaloric material is in direct contact with the liquid working medium, the evaporation of which is caused under heating by an applied electrical and/or magnetic field.

Preferably, a first electro- or magnetocaloric material element is integrated in the region of the first end of the heat pipe, and a second electro- or magnetocaloric material element is integrated in the region of the second end of the heat pipe.

When a heat pipe is used as a thermosiphon, in particular a vertical arrangement of the heat pipe or pipes is preferred in order to guarantee heat transport with a preferential direction.

Preferably, a first heat exchanger, in particular a cooling body, is arranged in heat-conductive connection with at least one first electro- or magnetocaloric material element, in particular at a lower end of the heat pipe, and a second heat exchanger, in particular a heating body, is provided at an upper end of the heat pipe.

Preferably, inside the heat pipe, a controllable thermal connection is created between the first and second end thereof, such as e.g. may be achieved by a pressure- or thermo-valve between the first and second end of the heat pipe.

When the e.g. electro- or magnetocaloric material element in the first heat transfer region, e.g. at the lower end of the heat pipe or thermosiphon, is in the electrical and/or magnetic field, the material heats up. In this way, the working fluid in contact with said material evaporates inside the heat pipe and rises upward or flows to the other end of the heat pipe. There the working medium vapor condenses on a condenser, which is preferably also made of or comprises an electro- or magnetocaloric material which at this time is not in an electrical and/or magnetic field. The evaporation/condensation process releases a very great quantity of heat from the first electro- or magnetocaloric material element of the first heat transfer region, preferably located at a lower end of the heat pipe, to the second material element of electro- or magnetocaloric material in the second, preferably upper heat transfer region. If now for example the upper electro- or magnetocaloric material, located at a second end of the heat pipe or in the second heat transfer region, is exposed to an electrical and/or magnetic field, and the field at the first heat transfer region (preferably the lower end of the heat pipe) is disconnected or this first heat transfer region is moved out of the electrical and/or magnetic field, the upper electro- or magnetocaloric material element or that in the second heat transfer region of the heat pipe heats up, and the other electro- or magnetocaloric material element (preferably lower or in the first heat transfer region) cools down, wherein a heat exchange between the upper second electro- or magnetocaloric material element and the first or lower electro- or magnetocaloric material element (first heat transfer region) is reliably avoided.

In its general basic arrangement, the invention also extends to the presence of just one electro- or magnetocaloric material as a heating structure for a working medium of the heat pipe, in particular a thermosiphon, in which a unidirectional heat transport is provided, and in the opposite direction merely a substance transport of the working medium is provided, e.g. the upper region of the heat pipe or thermosiphon contains merely a condenser or condensation structure for the working medium.

Conventional air conditioning systems usually work with actively pumped fluids as heat transfer media. Here, due to the convective heat transfer at the interface, the heat transmission from the electro- or magnetocaloric material to the fluid is the restricting factor of the air conditioning device. In contrast, according to the invention, by using the evaporation enthalpy of the fluid in heat pipes, per fluid molecule a substantially larger quantity of heat can be transported and hence the cooling power can be significantly increased by a combination of a heat pipe with electro- or magnetocaloric materials integrated or arranged therein.

However, stationary switchable field sources may also be provided for alternate field influencing of the first or second electro- or magnetocaloric material, e.g. an electromagnet which optionally influences the first or second electro- or magnetocaloric material.

Preferably, the air conditioning device is characterized by a heat pipe in conjunction with a source of an electrical and/or magnetic field, and preferably a relative mobility between the heat pipe and field generator, in particular for an alternate field influencing of the first or a second electro- or magnetocaloric material inside the heat pipe.

When an electromagnet is used, the field influencing of the electro- or magnetocaloric material may be controlled by the switching of the electromagnet, and in the case of use of electro- or magnetocaloric material in a first and a second heat transfer region which are “connected” together by the working medium, a relative movement between the field and electro- or magnetocaloric material can be avoided.

Preferably, firstly a condenser, in particular made of electro- or magnetocaloric material, and secondly an evaporator, in particular made of electro- or magnetocaloric material, are connected to the heat pipe of the air conditioning device, wherein the evaporator is exposed at least temporarily to an electrical and/or magnetic field of a field generator.

In a particularly preferred embodiment of the invention, the electro- or magnetocaloric material has an enlarged contact surface to an adjacent working fluid, in particular with a micro- or nano-structure, so that a very great heat transfer occurs between the electro- or magnetocaloric material on one side and the working fluid inside the heat pipe on the other, which fluid is evaporated by the field influencing of the electro- or magnetocaloric material.

Further preferred embodiments of the object of the invention are explained in the other subclaims.

To increase further the efficiency of such air conditioning devices, according to the invention an air conditioning device is provided with a heat pipe arrangement having a plurality of heat pipes arranged in series, each with electro- or magnetocaloric material elements arranged therein, and/or a plurality of electro- or magnetocaloric material elements integrated in a heat pipe (thermosiphon) which form several gas-tight segments (working regions) in the heat pipe.

In an advantageous embodiment of the invention, at least one thermal connecting element, in particular a controllable thermal connecting element, is arranged between two heat pipes or inside a heat pipe between two working regions, i.e. the heat transport from one heat pipe to an adjacent or successive heat pipe, or from a first working region to a second working region, may in particular be regulated and adjusted.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained in more detail below with reference to exemplary embodiments and attached drawings.

In the drawings:

FIG. 1 shows diagrammatically a heat pipe as an exemplary embodiment of an air conditioning device with at least one electro- or magnetocaloric material element in the region of one end, here the lower end, of a heat pipe formed as a thermosiphon;

FIG. 2 shows a heat pipe in a depiction similar to that of FIG. 1 but with additional heat transmitters on the cold side (bottom) and the warm side (top);

FIGS. 2A-2C show modifications of the electro- or magnetocaloric material body 4 in the above-mentioned exemplary embodiments and for the following exemplary embodiments of the structuring (surface enlargement) and electrical divisions (suppression of Joulean heat by eddy currents);

FIG. 3 shows a heat pipe in a depiction similar to those of FIG. 1 and FIG. 2, as a further exemplary embodiment with the active electro- or magnetocaloric material as a layer on a cold side (bottom);

FIG. 4 shows a cascaded arrangement of heat pipes in the manner of the heat pipe depicted in FIGS. 1 to 3 as air conditioning devices to widen the temperature differential or increase the heat- or cold-generating effect;

FIG. 4A shows a further example of a cascaded arrangement of a plurality of heat pipes similar to those in FIG. 4 but for a compact structure with a change of length/width ratio;

FIG. 4B shows a further exemplary embodiment of a cascaded heat pipe arrangement as a further exemplary embodiment of an air conditioning device in compact arrangement with length/width ratio modified in relation to FIG. 4A;

FIG. 5 shows a further exemplary embodiment of a heat pipe as a thermosiphon in a structured formation of the evaporator made of magnetocaloric material with integral heat conductor;

FIG. 5A shows a cascaded arrangement of heat pipes or thermosiphons according to the embodiment in FIG. 5, with thermal connection of the upper condensation arrangements with the superposed evaporator, made of magnetocaloric material, of the next stage by means of a heat conductor;

FIG. 5B shows a cascaded heat pipe or thermosiphon arrangement according to the embodiment in FIG. 5A, wherein the condenser arrangements of the two lower heat pipes or thermosiphons are formed at least partially from magnetocaloric material;

FIG. 6 shows a further exemplary embodiment of a heat pipe or thermosiphon with structured magnetocaloric evaporator with enlarged surface area, in a diagrammatic depiction similar to the preceding exemplary embodiments;

FIG. 7 shows a further embodiment of a heat pipe or thermosiphon in a diagrammatic depiction, with structured magnetocaloric material body with integral heat conductors;

FIGS. 8A, 8B show exemplary embodiments of heat pipes or thermosiphons in a diagrammatic depiction, with a magnetocaloric material in both the lower region (as evaporator) and in the upper region (as condenser), wherein FIG. 8A depicts a magnetic field influencing of the evaporator and FIG. 8B depicts a magnetic field influencing of the condenser;

FIGS. 9A, 9B show a further exemplary embodiment of a heat pipe or thermosiphon with a direction-dependent pressure valve, wherein FIG. 9A shows a depiction with open valve and magnetic field influencing of the evaporator with an oriented heat flow from bottom to top, and FIG. 9B shows a depiction with closed pressure-control valve and magnetic field assigned to the condenser;

FIG. 10 shows a temperature-time diagram for the exemplary embodiments of the heat pipes or thermosiphons in FIGS. 8A and 8B, with a diagrammatic depiction of the temperature development inside the heat pipe or thermosiphon;

FIGS. 11A, 11B show diagrammatically a cascaded arrangement of heat pipes or thermosiphons with a controllable thermal connection between the evaporator and condenser with assigned corresponding magnetic field sources, based on heat pipes or thermosiphons according to FIG. 9;

FIGS. 12A, 12B show a heat pipe with segmented inner structure with a plurality of working regions formed by electro- or magnetocaloric material elements; and

FIGS. 13A, 13B show a heat pipe in the depiction similar to those of FIG. 1 and FIG. 2 as a further exemplary embodiment in curved form, and a circulating system constructed from this with rotating generators of an electrical and/or magnetic field.

DETAILED DESCRIPTIONS OF THE PREFERRED EMBODIMENTS

In the context of the present application and the following explanations of various exemplary embodiments, the terms “heat pipe” and “thermosiphon” (as a special configuration of a heat pipe) are substantially synonymous, wherein in the context of the present invention, these should be understood not as isothermic heat conductors with even heat distribution in stationary state, but as oriented heat conductors in which heat transport takes place always only in one direction, namely from the evaporator side towards the condensation side, so that only a substance return of working medium takes place from the condensation side to the evaporator side with no backflow of heat.

The exemplary embodiments are explained as thermosiphons, i.e. as heat elements inside which the working fluid flows back under the influence of gravity.

To the extent that the invention or the exemplary embodiments thereof concern a thermosiphon, this is a heat pipe operated by gravity in an at least substantially vertical position.

However, other embodiments are conceivable in which e.g. centrifugal forces or externally applied forces ensure the substance transport (working medium) inside the heat pipe, or a multiple arrangement thereof.

The embodiment in FIG. 1 shows a thermosiphon 100 as an embodiment of a heat pipe in which a working medium 2 e.g. water, is present in liquid state under adapted pressure inside a housing 1 as a hermetically closed vessel; said working medium is heated and at least partially evaporated by an evaporator (here configured as a magnetocaloric material element) by the application of a magnetic field by the arrangement of a magnet 6 (here formed as a horseshoe) in the region of the evaporator element 4, in order to transform at least partially into a gaseous working medium 3 and rise up, i.e. flow from the evaporator element 4 in the direction of a condenser 5 which is arranged at the top inside the heat pipe or thermosiphon 100 and on which the gaseous working medium 3 condenses, or if a gas or vapor of the working medium is already distributed throughout the heat pipe (thermosiphon 100), it condenses on the condenser 5 there by a change of the evaporation-induced gas pressure, wherein a very great amount of heat is transmitted from the lower evaporator element 4 made of magnetocaloric material to the condenser 5 and released there as latent condensation heat. This may be utilized at the top of the heat pipe or thermosiphon 100; by removal or disconnection of the magnet 6 from the magnetocaloric evaporator element 4, the magnetocaloric material 4 cools by re-orientation of its magnetic moments and leads to a cooling of the environment to a temperature below the ambient temperature. The arrangement of the magnetocaloric material element 4—here designated the magnetocaloric evaporator 4—inside the heat pipe or thermosiphon 100 is essential, with the result of excellent heat exchange and heat transfer between the magnetocaloric material element 4 and the surrounding liquid or evaporated working medium 2 or 3, because of the heating/evaporation of the working medium 2 due to the magnetocaloric effect by the arrangement of the magnetocaloric material element 4 inside the magnetic field formed by the magnet 6 (preferably a permanent magnet or special arrangement of permanent magnets, such as for example a so-called Halbach cylinder or a linear Halbach array). In the so-called Halbach cylinder, individual blocks of permanent magnets are joined together into a cylinder, so that the direction of magnetization of the individual blocks is matched to each other, causing a particularly strong, homogenous magnetic field in the interior.

The electro- or magnetocaloric material may here be present e.g. as a sheet, porous solid body, foam, wire, powder, weave and/or thin layer on a substrate.

It is clear from the explanations above in the context of the present application that, instead of a magnetocaloric material element 4, an electrocaloric material element may be used, and accordingly instead of the magnet 6, an electrical field and corresponding generator e.g. a plate condenser may be used as a field source.

The magnetocaloric material element 4 may also lie in an electromagnetic alternating field of a switched electromagnet.

It is pointed out here that in the first exemplary embodiment, the first heat transfer region is formed between the magnetocaloric material element 4 and the working medium 3, whereas the second heat transfer region for the absorption of latent heat from the working medium gas 5 is formed by a heat exchanger as a condenser 5. The latter may however in turn consist of “reinforcing arrangements” of electro- or magnetocaloric material in its structure or contain such material, as will be depicted below with reference to further exemplary embodiments (FIG. 4, FIG. 5, FIGS. 8 to 11 and FIG. 12) for the arrangement of a plurality of sealed working regions inside a thermosiphon or heat pipe (segmented heat pipe).

In the exemplary embodiment of FIG. 2, the heat pipe or thermosiphon 100 is refined further in relation to the embodiment in FIG. 1, in that here also the heat exchanger elements 7 (heat transfer cold side) and 8 (heat transfer warm side) in contact with the top (warm) and with the bottom (cold) respectively are depicted.

Otherwise, the mechanism for the generation of heat or cold because of the electrocaloric or magnetocaloric effect corresponds to the mechanism described above.

Although in the exemplary embodiments below only the use of magnetocaloric materials in a magnetic field is explained, this should be understood to be merely exemplary. In the same way and with the same mixtures, electrocaloric materials in an electrical field could also be used in these exemplary embodiments.

FIGS. 2A, 2B, and 2C show diagrammatically, amongst others, various embodiments of the magnetocaloric material element 4 (applicable accordingly also to an electrocaloric element) as possible modifications, wherein in FIG. 2A the magnetocaloric material 4 is structured additionally, to improve the heat transfer, with heat conductors 10 which extend partially (FIG. 2A) or completely into the magnetocaloric material element 4, in order to improve the heat transfer to the working medium 2/3 inside the heat pipe or thermosiphon 100.

The electro- or magnetocaloric material 4 may here be present for example as a sheet, porous solid body, film, foam, wire, tube, powder and/or coating.

In FIG. 2C, the magnetocaloric material 4 is also combined with electrical isolator layers 4B which serve to eliminate possible eddy currents inside the magnetocaloric material 4 in conjunction with electromagnetic alternating fields, and hence an undesirable heating because of the Joulean heat can be minimized.

As also indicated in FIG. 1 on the left with a double arrow next to the magnet 6, after heating of the magnetocaloric material element 4 by the magnetic field of the magnet 6, the latter is moved preferably along the thermosiphon 100 so that the magnetocaloric material element 4 is no longer in the area of influence of the magnet 6, and a corresponding cooling takes place by reset of the moments of the magnetocaloric material to achieve a cooling effect at the heat transmitter 7. Evidently, on use of an electromagnet, this can simply be switched off, or the thermosiphon or heat pipe 100 can also be moved longitudinally relative to a stationary magnet 6 in order to achieve the same effect. Usually however it would be sensible to move the magnet 6 along the heat pipe or thermosiphon 100.

The embodiment of the heat pipe or thermosiphon in FIG. 3 differs from the designs explained above only in that here the magnetocaloric material element is formed as an internal coating 11 in the lower region of the housing 1 of the thermosiphon or heat pipe 100, in order to improve the heat transfer and hence improve the evaporation effect of the electrocaloric coating 11 in relation to the liquid working medium of the heat pipe or thermosiphon 100.

FIG. 4 now shows a cascaded arrangement, with several steps arranged successively above each other, of heat pipes or thermosiphons of the type described above which here are formed in particular in the manner shown in FIG. 3 with the magnetocaloric material element formed as an inner coating 11 in the lower region of the respective heat pipe or thermosiphon 100, wherein a corresponding multiple effect (increased temperature range) is achieved for the air conditioning effect achievable by a single thermosiphon or single heat pipe 100 on its top or bottom side. To establish a heat flow directed from the bottom to the top, the magnet arrangement 6 is moved from the bottom to the top as indicated by the double arrow on the left. In this way therefore, the cooling effect or temperature differential is multiplied accordingly on the underside of the cascaded arrangement for the heat transmitter on the cold side 7, and also the effect of the heat transmitter 8 on the upper warm side of the multiple arrangement.

In FIG. 4, the same magnet G′ is shifted in steps from the lower thermosiphon or heat pipe 100 to the middle and top ones in the positions indicated, or if electromagnets are used, these are switched on and off in this order.

In this way, an oriented heat transport is generated only from bottom to top in the direction of the heat transmitter 8 on the warm side, while simultaneously the re-orientation of the magnetic (or electrical) moments of the magnetocaloric (or electrocaloric) material 11 (inner coating) ensures the cooling of the heat transmitter 7 (cold side).

In a similar fashion to FIG. 4, the multiple arrangement of heat pipes or thermosiphons 100 in an even more compressed and compact configuration in FIG. 4A leads to a reinforcement of the air conditioning effect on both the warm side (heat transmitter 8) and on the cold side (heat transmitter 7).

The magnet arrangement 6 is moved from bottom to top so that, successively from bottom to top, the magnetocaloric inner coatings 11 on the underside of the corresponding heat pipes or thermosiphons 100 are heated by the corresponding magnetic field influence, and also the magnetocaloric coatings 11 outside the upper magnetic field (magnet 6) are cooled.

FIG. 4B is based on the same working principle. Here only the heat pipes or thermosiphons in an integral housing arrangement 1 are compressed more greatly, in order to meet specific structural requirements for the air conditioning device.

Otherwise, reference is made to the explanations given above for FIG. 4A.

FIG. 5 shows diagrammatically another embodiment of a heat pipe or thermosiphon 100 with advantageously further improved heat transfer characteristics of the magnetocaloric material 4, here divided into several conical elements by the use of heat conductors 10 integrated in the magnetocaloric material 4, wherein preferably these magnetocaloric evaporators or absorbers are placed in an interface between the liquid and gaseous phases 2 and 3 of the working medium, and hence above the “sump” which designates the wet part in the thermosiphon or heat pipe 100. In this way, firstly the evaporation effect of the magnetocaloric elements 4 is increased further by their structuring, and secondly on resetting of the magnetic moments after removal or e.g. relative upward movement of the magnet 6, an improved transfer of cooling power from the magnetocaloric material element 4 to the heat transmitter 7 (cold side) is guaranteed.

Although not depicted here, a further improvement in the internal thermal contact between the magnetocaloric material 4 and the working medium 2 or 3 may be achieved by formation of the magneto- or electrocaloric material with a good wetting surface, and e.g. micro- or nano-structures may be used to configure the heat transfer surfaces as large as possible.

Although this is also not explained in more detail or depicted here, also a Peltier element may be thermally coupled to such an “integrated” heat pipe or thermosiphon 100 which also contains at least one electro- or magnetocaloric material and to which at the same time, temporarily, an electrical field or magnetic field or electromagnetic field is assigned, in order to maximize a temporally coordinated heat transfer between the heat pipe or thermosiphon 100 and the heat transmitter 7.

As explained below, but also as is clear in conjunction with the already cascaded (multiple) arrangements of heat pipes or thermosiphons 100 connected in series, several similar heat pipes or thermosiphons or those using different electro- or magnetocaloric materials may be coupled together, in particular also via interposed heat exchangers, wherein because of the rising temperatures from bottom to top in a heat pipe or thermosiphon column, preferably the magnetocaloric materials in heat pipes or thermosiphons 100 at higher temperature have a different (higher) Curie temperature than the magneto- or electrocaloric materials which are arranged closer to the cold side of such a multiple arrangement.

Since the magnetocaloric effect of a magnetocaloric material is greatest in the vicinity of its Curie temperature, preferably the respective magnetocaloric material is operated in this temperature range as a working temperature.

In any case it is ensured that either by additional switching or valve elements, or by gravity, always a unidirectional heat flow takes place, generally from bottom to top or from the cold side to the warm side.

Such a heat flow may also be supported or provoked by the additional application of external forces, e.g. centrifugal forces in conjunction with a rotating system.

FIG. 5A shows a multiple arrangement i.e. a triple arrangement of thermosiphons or heat pipes 100, as shown as individual elements in FIG. 5, wherein the heat conductors 10 connected directly to the respective magnetocaloric material elements 4 are each connected with good thermal conductivity to the condenser 5 of the preceding stage.

Here again, the same magnet arrangement 6 is moved from bottom to top according to the double arrows shown, so that a unilaterally oriented heat flow takes place from bottom to top, so that the magnetic field of the magnet 6 moves from bottom to top accordingly along the multiple arrangement of thermosiphons or heat pipes 100 (which are received in a common housing 1).

In the right-hand multiple arrangement in FIG. 5B, the air conditioning effect of the total arrangement is further increased significantly in that, in contrast to the preceding depictions, not only the evaporator consists of electro- or magnetocaloric material 4 but also at least partially the condenser 5, so that when the magnetic field or magnet arrangement 6 is moved up from the bottom position shown in FIG. 5B to the middle position, an increased heat transport can be guided from the condensers of the respective heat pipes to the superposed evaporators of the heat pipe lying above.

This again substantially increases the efficiency of the total arrangement.

Here again, the same magnet arrangement 6 is moved from bottom to top according to the heat flow, so that increasingly, the lower magnetocaloric material 4 or the magnetocaloric material provided on both the evaporator and condenser sides and arranged in the middle level, after it has moved outside the magnetic field, cools with a re-orientation of the magnetic moments and in this way the cooling or chilling effect or temperature differential of the entire arrangement of heat pipes or thermosiphons 100 is multiplied.

In the further embodiment of an air conditioning device as a heat pipe or thermosiphon 100, the electro- or magnetocaloric material element 4 itself is provided as a lower closure of the heat pipe or thermosiphon 100, i.e. in practice forms the lower wall element of the heat pipe or thermosiphon 100, in the size of surface configuration (here formed as a zigzag) for the heat transmitter or heat exchanger 7 on the cold side.

In conjunction with additional heat conductors 10, in this way a connection with excellent thermal conductivity is created between the heat transmitter 7 (cold side) on one side and the magnetocaloric element on the other, and also with regard to the evaporator effect of the magnetocaloric element 4 in relation to the liquid working medium 2.

In this way, the thermal resistance inside the arrangement can be reduced further and the magneto- or electrocaloric effect utilized as well as possible. Here again, the magnet 6 or corresponding magnetic field ensures the heating of the magnetocaloric material 4 and its function as an evaporator for the liquid working medium 2, wherein then for cooling the magnetic field is switched off or the magnet (e.g. ring magnet 6) is moved upward or otherwise away, so that the magnetocaloric material element 4 no longer lies in its field region.

Such a heat pipe or thermosiphon 100 is also particularly suitable for forming a multiple arrangement with columnar succession, in some cases also with the condenser 5 formed at least partially as a magnetocaloric material element.

This also applies for the further embodiment in FIG. 7, in which firstly also a structured closure of the thermosiphon or heat pipe 100 is formed from the magnetocaloric material, but which secondly also at least partially is provided with integrated heat conductors 10 and provides a large heat transfer area to the heat transmitter 7 (cold side).

In the same way as for the exemplary embodiment in FIG. 6, here again a particularly good heat transfer characteristic is guaranteed with regard to the effect of the magnetocaloric element 4 as the evaporator, in particular due to the specifically enlarged contact surface due to the multiplicity of conical magnetocaloric elements, and also in regard to the use of heat conductors towards the cold side 7.

The effects correspond to those already described above for the other exemplary embodiments.

As already mentioned in relation to the exemplary embodiment according to FIG. 5B, for the multiple arrangement of magneto- or electrocaloric material elements 4 inside the single heat pipe or thermosiphon 100 in conjunction with a columnar multiple arrangement, this particularly efficient embodiment for a highly effective air conditioning device is indicated diagrammatically and explained again in FIGS. 8 to 11; here too, the formation of an oriented heat flow from bottom to top (in the case of a thermosiphon) or, independently of spatial position, from a first end (cold end) to a second end (warm end) is essential.

As FIG. 8 illustrates for the starting state, in the heat pipe or thermosiphon 100, a first electro- or magnetocaloric material (the description below always relates to the case of a magnetocaloric material and a magnetic field) is arranged at the lower end as an evaporator for a working medium inside a heat pipe or thermosiphon 100 which is under a reduced pressure; here a further magnetocaloric material element 4, preferably having a higher Curie temperature and here designated MC material 1, is arranged at the upper end of the thermosiphon or heat pipe 100, so that—as already explained—the first magnetocaloric material (MC material 2) located in the magnetic field (B field) heats up and acts as an evaporator, wherein a heat flow Q rises upward and condenses at the magnetocaloric material MC material 1, wherein the liquefied working medium flows back down again under gravity.

The first magnetocaloric material MC2 thus forms a first heat transfer region with the surrounding working medium, and the second magnetocaloric material MC1 forms a second heat transfer region with the working medium 3.

The temperature T1 of the upper magnetocaloric material MC1 is in this case lower than the temperature T2 of the lower magnetocaloric material MC2 which is in the magnetic field 6 of the magnet 6.

The starting point for a multiple arrangement is now the upward displacement of the magnetic field, i.e. of the corresponding magnet 6, so that the upper magnetocaloric material MC1 is heated using the magnetocaloric effect, while the lower magnetocaloric material cools with re-modification of its magnetic poles, but in this case no heat transport takes place and also no backflow of working medium under gravity; rather, heat from the environment is transferred onto the lower magnetocaloric material with the lower temperature T2, which is thereby cooled.

To promote this effect and establish an oriented heat flow from bottom to top, in addition the heat pipe or thermosiphon 100 may be configured as a thermal diode with an additional switchable heat flow, valve-supported or controlled; such an embodiment is shown in FIG. 9A for an open valve 15 which opens under a pressure difference because of the evaporation of the liquid working medium, in order to guide the heat flow Q in the direction of the upper magnetocaloric material MC1, while on the right-hand side FIG. 9B shows the closed state of the valve 15 due to the heating of the upper magnetocaloric material and the then higher pressure above the valve 15, preferably formed as a ball valve. A plurality of valves may also be provided for a switchable heat flow.

FIG. 10, in a temperature-time diagram, shows the function of the heat pipe or thermosiphon 100 provided with two magnetocaloric materials MC1 and MC2 arranged in the interior thereof, and hence the action as an air conditioning device due to the electro- or magnetocaloric effect, namely with displacement of the magnetic field or magnet 6 from bottom to top to create correspondingly cascaded arrangements in order to increase the efficiency.

The diagram shows qualitatively firstly the temperature development for the magnetocaloric material 4 MC1 at the upper end of the thermosiphon or heat pipe 100, and secondly the temperature development of the lower magnetocaloric material 4 MC2 at the lower end of the heat pipe or thermosiphon 100, wherein evidently in practice these graphs are asymptotic and do not run strictly linearly.

The explanation of the temperature-time diagram in FIG. 10 shows the function of the air conditioning device directly, so no additional explanations appear necessary.

FIG. 11 finally shows another cascaded arrangement of heat pipes or thermosiphons 100, with interposition of heat exchangers 20 and controllable thermal connections which are indicated in the diagrams in FIGS. 11A and 11B as black transverse bars. These controllable thermal valves may be similar to the ball valves 15 in FIGS. 9A and 9B, or also other switch elements for controlling the heat flow from bottom to top in the depictions of FIGS. 11A and 11B. Also, again, the displacement of the magnet 6 and hence also the magnetic field for continuous heat transport is illustrated. The controllable or switchable thermal connecting elements 20 may be implemented in varying ways and serve to improve the thermal connection between the heat pipes or thermosiphons 100 and the heat convection to the environment.

In a further exemplary embodiment of the present invention which is depicted in FIGS. 12A and 12B, and which to a certain extent may be regarded as a modification of the exemplary embodiment with a plurality of heat pipes or thermosiphons 100 according to FIGS. 11A and 11B, in the exemplary embodiment according to FIGS. 12A and 12B, a single heat pipe or single thermosiphon 100 is shown which is divided into a series of working regions 20/1, 20/2 and 20/3, wherein the number of divisions of the thermosiphon or heat pipe 100 is variable or, like the size of the heat pipe 100, can be adapted to the particular application.

Each working region 20/1 to 20/3 is delimited by a magnetocaloric material element 4, wherein here again (as in the coupling of several heat pipes in FIGS. 11A and 11B), the working regions 20/1 to 20/3 use a common magnetocaloric material element 4, multiplying the cooling power to a cooling body (heat exchanger 20) at the lower end or a heat transmitter (heat exchanger 20) at the upper end of the thermosiphon 100.

The magnetocaloric material elements 4 seal pressure-tight against the inner wall of the heat pipe 100 in order to enclose pressure-tight between them the working regions 20/1 to 20/3 and hence the working medium situated in the respective regions, wherein—as already explained above—controllable thermal valves 15 may be provided inside the working regions 20/1 or 20/3 (FIG. 12A) or at another point (concerning the heat exchanger 20 or middle working region 20/2). The magnet arrangements 6, in their active arrangement shown in FIGS. 12A and 12B for the arrangement of heat pipes 100 shown there, are each able in this case—due to double magnets—to influence the magnetocaloric material elements 4 belonging to different working regions 20/1 to 20/3.

In other words, in the arrangement of FIG. 12A, the magnetocaloric material element 4/2 and the “next highest” magnetocaloric material element 4/4 lie in the heat-generating influence of the magnetic field of the magnet arrangement 6, while the magnetocaloric material elements 4/1 and 4/3 are not field-influenced and therefore are actively cooled. Conversely, in the arrangement according to FIG. 12B, the magnetocaloric material elements 4/1 and 4/3 each lie in the influence of the magnetic field of the magnet arrangement 6 and form a heat source for the working medium 3 in the superposed working regions 20/1 and 20/3.

The arrangements according to the exemplary embodiments in FIGS. 11A and 11B, and FIGS. 12A and 12B, may evidently also be combined, i.e. heat pipes may be combined into a heat pipe cascade, which in turn may consist in the interior—in any case partially—of a multiplicity of working regions, i.e. individual heat pipe elements.

Here again, preferably different magnetocaloric materials with different Curie temperatures are used advantageously, because of the temperature level increasing in the vertically upward direction.

FIG. 13A shows a heat pipe similar to that of FIG. 1 and FIG. 2 in a further exemplary embodiment in curved form. The form of the heat pipe is generally less decisive for its function than the position. FIG. 13B shows a system constructed from curved heat pipes with generators of an electrical and/or magnetic field rotating about point Z. Due to the field generators rotating about point Z, a continuous heat transport can be achieved.

In further refinements of the present invention which follow the linking of working medium and electro- and/or magnetocaloric material in an electrical and/or magnetic field as a heat generator, it is also possible to use electro- or magnetocaloric material with a negative electro- or magnetocaloric effect, in which precisely the opposite effects occur, wherein this in any case entails a corresponding “reversal” of the arrangement of the field generators.

Also, a combination of electro- or magnetocaloric material elements with firstly conventional (positive) and secondly negative electro- or magnetocaloric effect, and/or inverse caloric effect, is conceivable. One exemplary embodiment in this case would be that all electro- or magnetocaloric material elements are held simultaneously under the influence of an electrical and/or magnetic field, or all removed from the field influence simultaneously, which in particular corresponds to an “immobile” i.e. stationary arrangement, as e.g. would advantageously be achievable by the use of an electromagnet.

The invention creates an extremely effective air conditioning device which includes an internal connection of electro- or magnetocaloric materials inside a heat pipe or thermosiphon, both with at least one such element and with a plurality thereof, in particular for the construction of cascade-like arrangements. 

1. An air conditioning device comprising at least one heat pipe (100) which contains at least one working medium, at least one electro- or magnetocaloric material (4) is integrated in the heat pipe (100), and under at least temporary influence of at least one of an electrical or magnetic field, and a heat transport (Q) oriented from a first heat transfer region between the at least one of the electrocaloric or magnetocaloric material (4) and the working medium (2) to a second heat transfer region of the working medium (2).
 2. The air conditioning device as claimed in claim 1, wherein the heat pipe (100) contains a plurality of heat transfer regions between a plurality of the at least one of electro- or magnetocaloric material elements (4) and the at least one working medium (2).
 3. The air conditioning device as claimed in claim 2, wherein the first heat transfer region comprises at least one first one of the electro- or magnetocaloric material elements (4) in a region of a first end of the heat pipe (100), and the second heat transfer region comprises at least one condenser in a region of a second end of the heat pipe (100).
 4. The air conditioning device as claimed in claim 3, wherein the condenser comprises an electro- or magnetocaloric material element (4) or is connected to or formed from such an element.
 5. The air conditioning device as claimed in claim 3, further comprising at least one first heat exchanger (7) in thermally conductive connection with the first electro- or magnetocaloric material element (4), and a second heat exchanger (8) in thermally conductive connection with at least one of the condenser or a second electro- or magnetocaloric material element (4) at a second end of the heat pipe (100).
 6. The air conditioning device as claimed in claim 1, further comprising a controllable thermal connection (15) between the first and second heat transfer regions.
 7. The air conditioning device as claimed in claim 6, wherein the controllable thermal connection (15) is a pressure- or thermo-valve (15) between the first and second heat transfer regions.
 8. The air conditioning device as claimed in claim 1, further comprising a field generator (6) of at least one of an electrical or magnetic field.
 9. The air conditioning device as claimed in claim 8, wherein a relative mobility is provided between the heat pipe (100) and the field generator (6) of the at least one of the electrical or magnetic field.
 10. The air conditioning device as claimed in claim 8, further comprising a condenser (8) provided in combination with an electro- or magnetocaloric material (4) and an evaporator, containing or including electro- or magnetocaloric material, at least the evaporator being temporarily in the at least one of the electrical or magnetic field of the field generator (6).
 11. The air conditioning device as claimed in claim 1, further comprising a first said electro- or magnetocaloric material element (4) in the first heat transfer region, and a second said electro- or magnetocaloric material element (4) in the second heat transfer region, wherein the two electro- or magnetocaloric material elements (4) lie alternately in at least one of electrical or magnetic field of a field generator (6).
 12. The air conditioning device as claimed in claim 1, wherein the electro- or magnetocaloric material element (4) has an enlarged contact surface to an adjacent working fluid (2).
 13. The air conditioning device as claimed in claim 1, wherein the heat pipe (100) is connected in thermal coupling to at least one Peltier element.
 14. The air conditioning device as claimed in claim 1, wherein the at least one heat pipe (100) comprises a plurality of heat pipes that are connected in series, in a substantially vertical arrangement.
 15. The air conditioning device as claimed in claim 1, wherein the at least one heat pipe (100) is configured as a switched thermal diode (heat flow in one direction only).
 16. The air conditioning device as claimed in claim 1, wherein an oriented heat flow takes place from a first end to a second end of the heat pipe as a result of a rotation-induced centrifugal force.
 17. The air conditioning device as claimed in claim 1, wherein at least part of a housing or a wick of the heat pipe (100) is formed of electro- or magnetocaloric material.
 18. The air conditioning device as claimed in claim 1, further comprising a structured evaporator of electro- or magnetocaloric material (4) with integrated heat conductor (10).
 19. The air conditioning device as claimed in claim 1, further comprising a structured evaporator of electro- or magnetocaloric material (4) connected thermally conductively to an integrated heat conductor (10).
 20. The air conditioning device as claimed in claim 1, further comprising a structured closure of the heat pipe made of electro- or magnetocaloric material (4) with a plurality of heat conductors (10) inside the structured closure in thermally conductive contact with a heat transfer element (7).
 21. The air conditioning device as claimed in claim 1, wherein the heat pipe (100) includes a plurality of electrical isolator elements (4 b) inside the magnetocaloric material (4).
 22. The air conditioning device as claimed in claim 1, further comprising at least one thermal connecting element (15; 20) between two successive ones of the heat pipes (100).
 23. The air conditioning device as claimed in claim 2, wherein in the heat pipe (100), a plurality of working regions (20/1 to 20/3) are provided each delimited by an electro- or magnetocaloric material element (4), and a working fluid is contained in each of the working regions.
 24. The air conditioning device as claimed in claim 23, further comprising a controllable thermal connection (15) in at least one working region (20/1 to 20/3) of the heat pipe (100).
 25. The air conditioning device as claimed in claim 1, further comprising an at least partial arrangement of electro- or magnetocaloric material with negative electro- or magnetocaloric effect or inverse caloric effect.
 26. The air conditioning device as claimed in claim 25, further comprising a combination of electro- or magnetocaloric material with non-inverse and inverse electro- or magnetocaloric effect inside the heat pipe, and a stationary arrangement of a switchable field generator (6) and the heat pipe (100) relative to each other.
 27. The air conditioning device as claimed in claim 1, wherein a Curie temperature of the electro- or magnetocaloric material (4) is adapted to a respective local temperature or working region of the heat pipe (100) in which the electro- or magnetocaloric material (4) is arranged. 